First get a vcds scan done for any faults. It could be a faulty sensor ... . Any garage should be able to do it (£30+)
Audi used to do a free health chech last year, might be worth checking if they still do . https://m.audi.co.uk/owners-area/maintaining-your-audi/audi-health-check.html
Here is a map that you can find others who have vcds and do a check for small fee ( map works on pc better then phone )
http://www.vwaudiforum.co.uk/forum/showthread.php?t=134957